1. Field of the Invention
The present invention relates generally to a system, method and apparatus for filling a container. More specifically, the present invention relates to a system, method and apparatus for vacuum-assisted filling of medicinal capsules with a precise dosage of dry powder pharmaceutical.
2. Related Art
In medicine, it is often desirable to administer various forms of medication to patients. A well known method of introducing medication into the human body is the oral ingestion of capsules. In another method, a patient may inhale certain medications through the nose or mouth. Inhalable medications come in numerous forms, including solids that are typically in the form of fine, dry powders. Specialized devices, such as inhalers, are typically provided to assist the patient in directing these fine powder medications through an airway and eventually into the lower respiratory tract. Various means for loading an inhaler with a proper dose of medication prior to use are known, including the use of capsules. For example, U.S. Pat. No. 5,787,881 discloses an inhaler that is used with encapsulated dry powder medicaments. Such devices require that capsules containing precise doses of medicament be available. The capsules are punctured and then inserted into the inhaler for inhalation of the medicament contained therein.
Countless other applications as well rely upon containers containing a specified amount of any of a number of materials. Many devices are known for filling such containers. However, each of these devices suffers certain drawbacks. U.S. Pat. No. 5,743,069, for example, discloses a metering device for medical applications. In this device, metering members are used to mechanically meter dosages of pharmaceutical through a plurality of holes, and eventually into a plurality of capsules. However, such mechanical metering devices, which rely only on mechanical members and gravity to apportion a particular dose of powder from a larger supply thereof, may lead to inaccurate doses. Such inaccuracies can result from, among other things, air pockets or clumps of powder in the supply. In addition, medical applications relating to inhalable medicaments may involve the handling of very fine, low-density powders. It has been found that these powders are difficult to handle due to their tendency to aerosolize, or become airborne, at the slightest provocation. Thus, a device for the metering of such powders must be designed with this quality in mind.
U.S. Pat. No. 5,826,633 discloses a powder filling apparatus for transferring an amount of powder to a receptacle. While the device addresses a problem of conglomerated powder through the use of a fluidizing means, the device is rather complex. Included are a variety of mechanical parts having relatively complicated interactions, and two motors requiring an external power supply. In addition, sources of vacuum and/or pressure are required.
Other devices, such as that disclosed in U.S. Pat. No. 5,809,744, address a problem of preventing aerosolization of fine powders, also through application of a vacuum. However, the device of U.S. Pat. No. 5,809,744 draws a vacuum directly through a container, such as a filter bag, into which a material such as coffee is to be vacuum-packed. Because such a device utilizes a vacuum for packing, it is not readily suitable for metering an accurate amount of a material for delivery to a non-porous container. Such a device cannot fill containers such as medicinal capsules, through which a vacuum is not easily drawn. In addition, medical applications regularly require high accuracy on a far smaller scale of dosage than the disclosed larger-scale device could offer.
Still other devices, such as the material apportioning apparatus disclosed in U.S. Pat. No. 4,671,430 and the powder filler disclosed in U.S. Pat. No. 4,949,766, attempt to overcome the above problem by apportioning material in a different container from that which is intended to eventually contain the apportioned amount. However, such devices fail to provide the simplicity of design and ease of use sought by those in the art.
Other conventional capsule filling machines have other disadvantages. Typically such conventional machines are designed to pack large amounts of powders into capsules, and are not optimal for delicate porous powders. Additionally, such conventional machines require a large volume of powder (e.g., greater than 500 ml) to prime the machine. Consequently, for some protein powders, in excess of $100,000 worth of powder is wasted just to prime the machine to fill one capsule.
Thus, there is a need in the art for an improved method and apparatus for filling containers with a precise dosage of dry powder. Specifically, what is needed is a method and apparatus capable of consistently delivering a precisely metered dose of dry powder medicament to a capsule. Preferably, such a device would further be simple in design and easy to use, through either manual or computer-controlled operation. The device would also be adapted to handle the low-density fine powders often present in medical applications, and to vacuum pack such powders into relatively small and highly accurate doses for delivery to a container, using a small priming volume. The present invention, the description of which is fully set forth below, solves the need in the art for such an improved method and apparatus.